Claude Opus 5 vs OpenAI: GPT-5.6 Luna Pro
Compare Claude Opus 5 by Anthropic against OpenAI: GPT-5.6 Luna Pro by OpenAI, context windows of 1.0M vs 1.1M, tested across 54 shared challenges.
Our Verdict
Claude Opus 5
OpenAI: GPT-5.6 Luna ProRunner-up
No community votes yet. On paper, Claude Opus 5 has the edge — bigger model tier.
OpenAI: GPT-5.6 Luna Pro is 4.2x cheaper per token — worth considering if cost matters.
Too close to call
API pricing
Cost per 1M tokens
Claude Opus 5
Input
$5.00
Output
$25.00
OpenAI: GPT-5.6 Luna Pro
Input
$1.00
5.0× cheaper
Output
$6.00
4.2× cheaper
OpenAI: GPT-5.6 Luna Pro is cheaper on both — 5.0× input, 4.2× output
Writing DNA
Style Comparison
Similarity
46%
OpenAI: GPT-5.6 Luna Pro uses 31.4x more emoji
Claude Opus 5
OpenAI: GPT-5.6 Luna Pro
54%Vocabulary58%
21wSentence Length18w
0.40Hedging0.81
3.9Bold2.9
1.9Lists5.1
0.02Emoji0.54
0.71Headings1.10
0.05Transitions0.09
Based on 27 + 27 text responses
Research
What we learned reading every model
FAQ
